Photo-electric intaglio and relief engraving system



Jan. 28, 1936. w HOWEY 2,029,103

PHOTO-ELECTRIC INTAGLIO AND RELIEF ENGRAVING SYSTEM Filed March 15, 1932 2 Sheets-Sheet l INVENTOR ATTORNEY w. HOWEY 2,029,103 PHOTO-ELECTRIC INTAGLIO AND RELIEF ENGRAVING SYSTEM Jan. 28, 1936.

Filed March 15, 1932 2 Sheets-Sheet 2 Attorney Patented Jan. 28, 1936 IU'NITED STATES PATENT OFFICE PHOTO-ELECTRIC INTAGLIO AND RELIEF ENGRAVING SYSTEM Walter Howey, New York, N. Y.

Application March 15, 1932, Serial No. 599,034

2 Claims. (01. 178-5) My invention relates to a photoelectric intaglio device. It also shows a unit power system which and relief engraving system and it more espemakes the self-contained unit operative by simcially consists of the features pointed out in the ply plugging into an alternating source of current. claims. Fig. 5 is a diagrammatic view of a reversing 5 The purpose of my invention is to provide an switch and its related circuits, by means of 5 engraving system that is equally suitable for prowhich, from the same subject, an intaglio or re ducing intaglio and relief printing plates in color, lief engraving may be produced at will. suitable for textile or other printing; that auto- In utilizing my system I may employ whatever mat cally produces rotogravure printing plates alternatives or equivalents of structure or cirand the like and also produces embossing plates; cuits that the exigencies of varying conditions 10 that employs features of transmission and amplimay demand without departing from the broad fication which make possible the production of spirit of the invention. engraving at the point of transmission or at a Any desired subject is mounted for scanning distance therefrom; that also makes possible the by a photoelectric cell and associated amplifying 5 engraving of bas relief or three-dimensional surmeans. A material adaptable for ultimate emfaces from shaded subjects which have only two bossing or printing is mounted on a suitable supdimensions of area comprised in width and port to be engraved. The output leads from the length; that provides for the automatic engravamplifier to the engraving head are so arranged ing in relief or intaglio of embossing surfaces that when black or absence of light is scanned from any desired subject without resorting to by the photoelectric cell the magnets of the en- 20 manual manipulation; that avoids the preparagraving motor will cause the engraving tool to tion of a master and a duplicate die for em miss the surface. When white is encountered the bossing with its complicated steps that call for tool is caused to cut deeply into the surface and staging or processing and the use of expert hand when gradations of tone or variations of light and labor; that through the system or process hereshade are scanned the motor magnets will defi- 25 in described the production of engraved plates nitely and positively hold the tool at different is made entirely automatic. depths to remove varying areas from the surface This is a continuation in part of myapplication so as to cut a master die corresponding to the Serial No. 424,809, filed January 31, 1930, which details of the subject.

on March 15, 1932 matured into Patent No. To produce a mother or intaglio die the en- 30 1 849,544, graved master plate is removed from its mount- With these and other ends in view I illustrate ing and an unengraved plate or roll is substiin the accompanying drawings such instances of tuted for it. The synchronous scanning head adaptation as will disclose the broad underlying 20 or cutting and engraving head 2| are moved to features of the invention without ilirniting mythe starting point and at one edge of the subject 35 self to the specific details shown thereon and de- 2 and the receiving plate I4 the leads from the scribed herein. amplifier to the cutting head 2| are reversed in Figure 1 is a diagrammatic view of the related any suitable manner by a well known reversing electrical circuits in Fig. 2 of my Patent No. switch l5 or the relative movement of the en- 1,849,544, issued March 15, 1932. graving tool l3 may be reversed in any suitable 40 Fig. 2 is a diagram of an alternative electrical manner by changing the fulcrum of its operating circuit using vacuum tubes in push-pu11 arrangelever 22 so that when black is encountered in ment and showing means for rotating the copy scanning, the engraving tool would cut deeply at various degrees to prevent moire effects in the into the surface and when white is encountered engraving. the graver will miss the surface and when grada- 45 Fig. 3 is a diagrammatic View of yet another tions of tone are encountered the tool will enalternative electrical circuit, showing the use of grave with reversed relation tothat of cutting transformer coupling to amplify the modulated the master plate. For the engraving tool 13 used carrier frequency generated by a tone wheel or in the process of cutting the master plate a sec- 5 other source of alternating or pulsating current. ond graver may be substituted for cutting the 5 Fig. 4 is a diagram of a complete electrical cirmulti-plates to provide for better registry of cuit, showing the use of a well known form of master and mother dies in embossing or printdirect resistance coupled amplifier coupled to a ing and embossing. A simple method of bringing photoelectric cell which in the output of the pushabout the reversing action for cutting relief, or

pull tubes has an inductive magnetic engraving cameo, or intaglio engravings, referred to above, 55

of the same subject, a double pole double throw switch I5 is placed in the output of the amplifier ulation or the introduction of reversal as prac-' ticed in picture transmission by telephone or radio so as to change a positive to a negative or vice versa..

My process lends itself readily to the rapid and economical preparation of dies for die sinking stamping purposes to produce repetitions of designs, in relief or intaglio for striking medals and the like.

Substitution of engraving tools of variable area or shape in the alternating process of engraving and embossing master and mother dies permit of accurately engraving dies for embossing materials of varying degrees of thickness and this is a feature of the invention. In my application Serial Number 424,809 and on Figs. 2 and 3 there is shown an output meter 8 for observing the depth of the engraver. This method of regulating depth may be utilized in combination with the use of engraving tools of various shapes and cutting area. It also provides for great accuracy in engraving and mother dies for use in embossing materials of varying degrees of thickness. To simplify the work of embossing a heated tool may be used. This tool may be heated in any suitable manner.

In Fig. 2 is shown an improvement over the circuit of Fig. 1. Here a light I is shown focused on a piece of copy 2 from which it is reflected to a photoelectric cell 6 through a filter 4. The current generated by the photocell 6 is amplified by a sufficient number of stages of vacuum tube amplification 'l9 to cause it to control the output of the power tubes 24 arranged for pushpull operation. In the plate circuits of the power tubes 24 are the actuating coils I2 of the magnetic graving device, or cutting head 2|. The armature 25 associated with the coils I2 and the lever 22 is pivoted so as to cause the tool l3 to cut into the metal to depths corresponding to the intensity of the light reflected to the photocell 6 from the copy 2. An indication meter 8 in theplate circuit of the first tube 1 of the amplifier indicates the operating output of that tube which controls the further amplification of the rest of the circuit. An indicating device in the output of the amplifier or an indicator 23 mechanically controlled by the engraving lever 22 will show the tones that are being engraved at any instant. The holder 5 for the copy 2 is arranged (Fig. 2) so that it may be rotated for each successive scanning in case of color separation work, where more than one scanning is made of the same copy. This is to avoid a moire effect which aries from the interference of parallel lines when two cuts occur at acute angles to each other. The copy is rotated 30 degrees or more from the original or first scanning and it is then again scanned at other angles, to produce a second and a third engraving. When the engravings are printed successively, one impression on top of the other, a pleasing composite effect is secured without any interference of the two sets of lines that otherwise would produce an incongruous or moire effect.

It will be understood that the dotted lines in the transformer in the photocell circuits or by a tone-wheel 3 to break up the light before it reaches the cell 6. This is sometimes called a light chopper. Sources IQ of a conventional A. C. current may be controlled by a tuning fork of the proper frequency or a vacuum tube oscillator.

The dotted lines, as already mentioned, in the amplifying circuit may represent any number of amplifying stages (-9, 16, I1 and I8. The filament of the rectifier tube 21 may be excited by alternating current as shown or by direct current as desired. The rectifier may be of any type such as a copper oxide rectifier or a gaseous type tube rectifier. In this circuit, Fig. 3, a reverse current hook-up 28 is shown in place of the standard push-pull in the circuit of Fig. 2. That is, although the current fiowing in the resistors in the plate cicruit of the power tubes flows only in one direction for each tube, the current in circuit I0 and in the coils I2 of the engraving head 2| reverses when the flow of current is transferred from the plate circuit of one tube to the other. The reason for this is that the current flowing in one resistor is diametrically opposite that flowing in the other resistor.

When equal current flows in both resistors, there is no current flowing in the coils of the engraving head and the armature is held in the center of its total swing by the combined forces of the two opposing magnetic fields of the device. It will be understood, however, that the standard push-pull circuit may be substituted for the reverse current circuit without departing from the broad scope of the invention.

A diagram is shown in Fig. 4 'of a complete unitary circuit with its power supply I9, 29 for the photoelectric engraving machine as an independent and complete unit. The amplifying circuit I6, l1, l8, I9 is especially adapted to amplify with equal fidelity direct current and alternating current of any frequency encountered in the engraving process. Since, without the use of special means for introducing alternating components or carriers into the circuit, the currents to be amplified are direct currents of various amplitudes. This feature is of prime importance. At times the current generated in the photocell 6 may be of unchanging amplitude for a considerable time and at other parts of the picture the amplitude of the current may vary at the rate of from four .to six hundred times a second.

The source of rectified high voltage and alternating current filament supply is shown as a well known form of power output associated with its accompanying rectifier and filter circuits. Any other form of power supply circuit may be used which is found to be better from the standpoint of more perfect rectification and filtration with out departing from the broad spirit of the invention.

The method of reversing the action of the engraving device to cause it to engrave intaglio printing plates or embossing plates or relief printing plates from the same subject as is used for engraving a relief plate is shown in Fig. 5. The plates of the two push-pull power tubes 24 are connected to a reversing switch l5, so that when the switch is thrown in one direction the current will fiow in the circuit N, the ammeter H and controlling coils "of the engraving device in one direction and in the reverse direction when the switch is changed over.

By the use of this switch, it is possible to engrave a relief plate from either a positive or negative subject or an intaglio plate from the same. This is the simplest form of reversing mechanism it is possible to incorporate in the output of an amplifying system. Other means such as employing a phase reversal tube are complicated and do not serve the purpose any better.

In my patent application, Serial Number 424,809 there is shown and described a method for making engravings from continuous tone subjects suitable for relief or offset printing. My present process however provides for the engraving of plates suited for printing continuous tone copies of a continuous tone subject A blunt tool may be substituted for a tapered tool and a screen (not shown) interposed between the subject 2 and the photocell 6 in the scanning system so that the action of the screen in intercepting the light refiected from the subject will cause the tool It to cut an intermittent series of indentations of constant area but varying depth into the surface of a substance suitable for printing.

This substance may take the form of a plate or a roll, similar to the rolls used in rotogravure printing. The interrupter may take the form of the screen, as above outlined, or any other suitable method of interruption.

Tone, in photography, designates values of light and shade; in music or radio it represents values of frequency. In photography, a picture is referred to as having a continuous tone, to differentiate it from well-known, so-called, halftone-screen-line reproductions produced by relief or offset printing. An ordinary half-tone presents an optical illusion oftone, although it may be printed on white paper with black ink, in the form of innumerable almost microscopic dots of varying area and separations and uniform pitch. A continuous tone picture, such as a photograph, painting, or gravure reproduction of the same, when scanned with a photoelectric cell and associated amplifying system may set up no cyclic frequency. The current modulation of the photocell circuit,.during the process of scanning a photograph, is a modulation of amplitudes. These surges of direct current may be faithfully amplified by a direct current amplifier, such as has been indicated in my application Serial Number 424,809.

In telephotography or radio photography, it is customary to modulate a carrier wave with the picture amplitudes for purposes of transmission; In photoelectric engraving such as has been described in Pearne et al. Patent No. 1,719,621, modulation of the continuous tone components of a photograph may be found desirable, in which case the amplifying system may comprise transformer or other suitable coupling, however the amplifier output may be made as indicated by Fig. 1, of this application, to secure improved results.

A uniform modulation of the characteristics of the scanning may be set up by any one of the following methods: (a) interruption of the light beam; ((1) of the amplifier; (c) of the carrier; (d) periodic interruption of the reflection characteristics of the subject. The first three methods are well understood in picture transmission. Method (d), well known in the photoengraving art, may be used by interposing a ruled transparent screen, similar to a photoengravers screen, between the subject and the photocell to interrupt the reflected or transmitted light. The screen may be of the cross line variety. It may be ruled in parallel lines only, set at a suitable angle so that the ruled lines and the aperture frame of the photocell or its diaphragm will cause frequency interruptions during the process of scanning. The screen may be of the metzograph type with minute irregular optical gradations. The screen formation may take any design found suitable in ordinary photoengraving, and the screen separation characteristics may be imparted to the subject to be engraved by first photgraphing it through a screen or by using a proof of a half-tone photoengraving of the subject. However interposition of a ruled screen between the subject and the photocell makes the latter involved processes unnecessary. Any of the methods described may be used to impart to the carrier or amplifier a uniform frequency modulation suitable to photoelectric transmission or engraving purposes. This picture frequency modulation in turn may be used to modulate a high frequency carrier wave with the provision of means for rectification inthe receiving amplifier.

In addition to the forms of periodic interruption above outlined, the interruption may be confined to the engraving head, and it may be introduced in the form of a magnetic interrupter described in U. S. Patent No. 1,719,621, or it may be produced mechanically. I do not limit myself to any one prescribed form of interruption in the practical production of engraved plates in an automatic manner.

As photo or rotogravure printing does not depend for its effect upon the optical illusion of ordinary half-tone dots, it is obvious that the indentations of constant area and varying depth, in a printing surface, will on a gravure press equipped with fountains and rolls for distributing ink over the entire plate and a doctor for scraping the surplus ink from the surface of the plate, transfer to a printed sheet dense ink from deep indentations and less dense pigmentation from shallow indentations. I accomplish this by my rapid automatic photoelectric method of engraving continuous tone printing surfaces, which is a radical improvement over the highly complitone dot, common to a relief picture printing block. This method, obviously, could be applied to the engraving of black and white line work. Half-tone engravings might be made indirectly by inserting a low frequency chopper 3 between the subject 2 and the photocell B, or by inserting a one or two Way ruled transparent screen, similar to a half-tone screen between the subject 2 and the photocell 6, or by introducing some cooperating means of periodic interruption into the photocell or the amplifying circuit, or by causing the cutting tool I3 to rise and fall intermittently by mechanical or other means. A screened half-tone negative might be used for scanning or as an alternative a positive print, containing the-separation dots, might be made by the silver print or velox method from the halftone negative and this print in turn be made the subject for'scan'ning. In the Pearne et a1. patent referred to,'transformer coupling was employed. Consequently some one of the above methods became necessary to provide transformer coupled amplification to obtain sufiicient power to do the engraving.

The employment of such processes to break a continuous tone subject into discontinuous pulses, having a frequency characteristic are commonly employed in various methods of picture telephony and telegraphy by wire or radio and it is standard practice for a different purpose, that of transmission. It is easier to transmit variations in frequency, either directly or through carrier current modulation than it would be to transmit variations of amplitude only, without frequency modulation.

This practice has lead to the misconception of a photograph, painting, or other subject having continuous components of light and shade as also comprising a so called picture frequency. Actually, as expressed in terms of a photoelectric current, during the process of scanning a photograph, there may be no cyclic frequency but only a series of varying pulsations in amplitude, corresponding somewhat to light as defined by the l. A photo-electric engraver comprising a light sensitive scanner, a vacuum tube amplifier adapted to increase the strength of the output of the scanner, a graver, an actuating arm therefor, a bi-polar armature on the arm spaced apart from the graver, a separate coil for each pole connected in opposition to each other, a push-pull amplifier comprising a pair ofv amplifier tubes actuated by an amplified current from the scanner, connections from one coil to the plate of one of the push-pull tubes, and connections from the other coil to the plate of the other push-pull tube, and cooperating means for indicating the successive positions of the graver.

2. The method of photo-electrically engraving a pictorial subject, consisting in photo-electrically scanning a subject and engraving a surface in synchronism, in amplifying the output of said scanning, in causing said amplified output to control a -magnetic engraving device, and in adjusting a the static characteristics of the amplifier to control the zero position of the engraver prior to the photo-electric scanning, to cause the depth of engraving to be in accordance with the variations of the photo-electrical scanning of the subject.

WALTER HOWEY. 

